1. Field of the Invention
The present invention generally relates to a grid wire cleaning mechanism. More specifically, the present invention relates to a grid wire cleaning mechanism having a cleaning mechanism that cleans grid wires used in a charging device that charges the surface of an electrostatic latent image carrier of an image forming apparatus.
2. Background Information
An image forming apparatus includes an electrostatic latent image carrier, a developing device that supplies developer to the electrostatic latent image carrier, a charging device that charges the surface of the electrostatic latent image carrier, and an irradiation device that irradiates the surface of the electrostatic latent image carrier with laser light. In this image forming apparatus, first the surface of the electrostatic latent image carrier is charged by the charging device. The surface of the charged electrostatic latent image carrier is irradiated with laser light by the irradiation device based on image data, to form an electrostatic latent image on the electrostatic latent image carrier. Then, developer is supplied from the developing device to the electrostatic latent image carrier on which the electrostatic latent image is formed. In this way, a toner image is formed on the electrostatic latent image carrier.
Charging devices that charge the surface of electrostatic latent image carriers include scorotron charging devices. Scorotron charging devices include discharge wires, and grid wires disposed in opposition to the discharge wires and disposed along the electrostatic latent image carrier. A bias voltage is applied to the grid wires in this charging device. Thereafter the surface potential of the electrostatic latent image carrier is controlled to be constant by the grid wires. Corona products, specifically NOx, SOx, can adhere to the grid wires.
Some image forming apparatus include a wire cleaning mechanism to clean corona products adhering to the grid wires like that shown in Japanese Patent Application Laid-open No. H10-207191. This wire cleaning mechanism includes a discharge wire abrading member that can abrade the discharge wires, a grid wire abrading member that can abrade the grid wires, and a movement mechanism that moves the discharge wire abrading member and the grid wire abrading member in the direction that the wires are stretched. After, for example, a predetermined number of sheets has been printed, the discharge wire abrading member and the grid wire abrading member are moved in the direction that the wires are stretched by the movement mechanism, and the grid wire cleaning mechanism cleans both sets of wires.
In the grid wire cleaning mechanism in Japanese Patent Application Laid-open No. H10-207191, the wire cleaning operation is carried out after completion of printing a predetermined number of sheets, regardless of environment. If the humidity around the image forming apparatus is high, or specifically if the humidity near the grid wires is high, corona products (for example, NOx, SOx, and so on) are absorbed by moisture in the air, and liquefy on the surface of the grid wires. In other words, they become water droplets. The corona products have electrically insulating properties, but in the liquid state they are electrically conducting. Therefore, even if liquid corona products adhere to the surface of the grid wires, the electrical resistance of the grid wires does not increase.
If the grid wire cleaning device carries out the cleaning operation with liquid corona products adhering to the surface of the grid wires in this way, the liquid is spread over the surface of the grid wires as a whole. If the humidity drops, in other words if drying occurs, while the liquid is spread over the whole surface of the grid wires in this way, the corona products dissolved in the liquid solidify, so solid corona products adhere to the whole surface of the grid wires in an uneven manner. Here, the solid corona products have electrically insulating properties, so the electrical resistance of the parts of the grid wires where corona products adhere increases. This causes unevenness of charging the surface of the electrostatic latent image carrier, which causes faulty developing, such as uneven density in the images. In this case also the life of the grid wires is shortened. Corona products also adhere to the grid wire contact member, so the life of the grid wire contact member is also shortened.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved grid wire cleaning mechanism. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.